[U-Boot] [PATCH v2] [RFC] memsize.c: adapt get_ram_size() for address spaces >32 bit

[Scott Wood]

On 05/27/2010 02:57 PM, Wolfgang Denk wrote:
> Dear Scott Wood,
>
> In message<20100527194618.GC5915 at schlenkerla.am.freescale.net>  you wrote:
>> On Thu, May 27, 2010 at 08:16:28PM +0200, Wolfgang Denk wrote:
>>> get_ram_size() used to use "long" data types for addresses and data,
>>> which limited it to systems with less than 4 GiB memory. As more and
>>> more systems are coming up with bigger memory resources, we adapt the
>>> code to use phys_addr_t / phys_size_t data types instead.
>>
>> This cannot work as is.  The only systems where this makes a difference are
>> where physical addresses are larger than virtual pointers -- but you try to
>> shove the 64-bit physical offset into a 32-bit pointer.
>>
>> You need to create temporary mappings, if you really want to do this.
>
> ?
>
> Isn't phys_addr_t assumed to be the right data type to hold a
> physical address?

Yes.  But you can't dereference a physical address directly.

When you do "addr = base + cnt", you're throwing away the upper 32 bits.

"phys_addr_t *" is not a 64-bit pointer, it is a 32-bit pointer to a 
64-bit quantity.

-Scott